Women are born with every egg they’ll ever have. The count falls from about a million to roughly 25,000 by 37, and the eggs that remain keep aging. No one can make a new one. That’s the timer on fertility, and why IVF gets harder with age.
@Conception says it just built a way around it. From a blood draw, they grew human eggs inside a tiny ovary also made from stem cells. The eggs have begun meiosis, the special division that halves a cell's 46 chromosomes to 23. That halving is what makes an egg an egg. A world first, they say. It matters because the starting cell is skin or blood, so ovarian age stops setting the limit.
The road here ran through mice. In 2016 Katsuhiko Hayashi's lab turned a mouse skin cell into an egg, then live pups. Humans stalled for years. Mitinori Saitou's team reached the egg's ancestor, but no one could build the follicle an egg ripens in or start meiosis in a dish. Conception says it cleared both.
These eggs only began meiosis. They haven't completed it, nothing's been fertilized, nothing published, no safety data.
If it holds, it reaches cancer survivors, women in early menopause, women who started late, two-dad families. Half the world, at every age. This could be truly revolutionary.
I’m so excited to share this update on
@Conception –
We’ve generated the first early human eggs derived from stem cells.
This is a big deal -- the potential to redefine fertility is real.